High-intensity interval training (HIIT) is a brief exercise session comprised of a warm-up period, several repetitions of high-intensity exercise interspersed by moderate-intensity exercise for recovery, and finished with a cool-down period.

The intense exercise must be performed at 80% to 95% of a person’s estimated maximum heart rate without overexerting. The moderate-intensity recovery periods are performed at 40% to 50% of a person’s estimated maximum heart rate. It can last from 7 minutes to 30 minutes following the 2:1 ratio of exercise to recovery.

While athletes have been using HIIT as part of routine training, it has steadily gained popularity among casual exercisers and in the healthcare setting.

This popularity is due to the many advantages of HIIT that cannot be reaped from other forms of workout regimens. If you do not know the major advantages of HIIT, read on and you’ll likely want to perform HIIT from now on.

Improves overall health

• Aerobic and anaerobic fitness. Just this year, the Journal of Sport and Health Science published a study suggesting that HIIT may have more advantages by making peripheral muscle changes resulting in lesser negative training symptoms like fewer reports of dyspnea and leg discomfort. Another study suggests that HIIT increased excess post-exercise oxygen consumption better than steady-state aerobic exercise, indicating that it may be more effective at increasing total daily caloric expenditure.
• Blood pressure and cardiovascular health. Also in the same Journal of Sport and Health Science, it was found that patients with cardiovascular disease who performed HIIT showed improved functional capacity and quality of life without increasing medical risk. In addition, a separate analysis found that HIIT improved blood vessel function and markers of blood vessel health better than moderate-intensity continuous training.
• Insulin sensitivity. HIIT significantly lowers insulin resistance as opposed to continuous training and results in lower fasting blood glucose levels and higher metabolic rates. In 2016, a study published in Diabetologia found that HIIT done in high volumes improved insulin quality in metabolic syndrome participants without type 2 diabetes.
• Cholesterol profiles and abdominal fat, body weight, and muscle mass. This year, Medicine and Science in Sports and Exercise published a systematic review that found that minimally active adolescents who did 1 HIIT set 2 times a week plus 1 resistance training session, had significant improvements in fitness and body composition. Improvements were seen in visceral fat mass, VO₂ max, body fat percentage, and waist circumference-to-height ratio.

More efficient

A single HIIT session ranges from 4 to 30 minutes, making it an excellent way to maximize a workout in a limited time. Studies suggest that more progress is achieved in 15 minutes of HIIT performed 3 times weekly than in an hour of jogging on a treadmill. A 2011 study showed that 2 weeks of HIIT improves aerobic capacity as much as 6 to 8 weeks of endurance training.

More convenient

Almost any exercise works as HIIT if done at high intensity. This makes equipment unnecessary because running, biking, high knees, jumping lunges, and other plyometric workouts can all be done the HIIT way. This also means you can do your HIIT session at home with the help of structured HIIT protocols, in a fitness studio, or in a group fitness class.

Can be mixed up to prevent boredom

Because of HIIT’s versatility when it comes to duration, the form of exercise, equipment, and location, every HIIT session may vary. This makes different HIIT workouts appealing especially to those who get easily bored with a fixed routine over a prolonged period of time. As long as the workout has the common formula of 2:1 ratio of exercise to recovery periods like 40 seconds of hard sprinting alternated with 20 seconds of jogging, you’re good.

Safe even for patients

A review published in 2016 says that HIIT strategies for stable patients with chronic disease carry only a small risk when the prescribed exercise protocols are followed. A 2015 analysis found that HIIT resulted in greater improvements in VO₂ max. Researchers also suggested that in patients with T2D, HIIT is effective in positively changing body fat percentage and increasing peak power output. A 2014 review revealed that individuals with lifestyle-induced chronic cardiovascular or metabolic diseases who completed a HIIT program had better cardiorespiratory fitness, as measured by VO₂ max, than those who completed moderate-intensity continuous training.